Variable transformer having terminals held by core housing



April 1, 1969 w. w. SCHAPIRA ET AL 3,436,709

VARIABLE TRANSFORMER HAVING TERMINALS HELD BY CORE HOUSING Filed May 22,1967 wa /WI.

United States Patent 3,436,709 VARIABLE TRANSFORMER HAVING TERMINALSHELD BY CORE HOUSING William W. Schapira, Skokie, and Louis H.Berkelhamer,

Glencoe, Ill., assignors to Consolidated Electronics Industries Corp.,Skokie, 11]., a corporation of Delaware Filed May 22, 1967, Ser. No.640,194 Int. Cl. H01f 15/10 US. Cl. 336-192 6 Claims ABSTRACT OF THEDISCLOSURE Transformers are commonly made with a central core encased ina housing of plastic or other insulative material. The housing and coreare at least partially enclosed by a spirally wound electrical coil. Thecoil is connected to metal terminals which are fixedly mounted on thehousing by suitable connection means. A movable contact is usuallyconnected to a terminal on the housing and is positioned for engagementwith the coil to enable the output of the transformer to be varied. Theterminals of these prior art transformers are in turn connected toelectrical circuitry. A variable transformer constructed in the mannerset forth above is disclosed in United States Patent No. 2,985,857 toEllin et al.

Widespread usage of these prior art variable transformers clearlyindicates that they are generally satisfactory in service. However,these prior art transformers are relatively difiicult and expensive toassemble. One assembly problem involves fixedly mounting the terminalson the core housing. The metal terminals must be connected to theplastic housing with sufficient rigidity so that the terminals do notloosen when they are connected to the coil and the movable contactduring assembly. Of course, the terminals must also be fixedly connectedon the housing with sufficient rigidity to enable associated or exteriorcircuitry to be connected to the transformer without loosening theterminals.

Therefore, it is an object of this invention to provide a variabletransformer structure which overcomes the aforementioned limitations ofprior art constructions. Specifically, it is an object of this inventionto provide an inexpensive means for fixedly mounting terminals of avariable transformer on an insulative housing for a core of thetransformer.

It is another object of this invention to provide a combination housingand terminal assembly having relatively few components.

These and other objects and features of the invention will become moreapparent upon a consideration of the following detailed descriptiontaken in connection with the accompanying drawings wherein:

FIGURE 1 is an exploded perspective view of a transformer including acore housing upon which terminals are mounted in accordance with apreferred embodiment of the invention;

FIG. 2 is an exploded perspective view of the core housing and core ofFIG. 1;

FIG. 3 is an enlarged perspective View, taken along the line 3-3 of FIG.2, illustrating the structure of a terminal mounting section which isintegrally formed with one section or element of the core housing ofFIG. 2;

FIG. 4 is an enlarged sectional view, taken along the line 44 of FIG. 3,illustrating a cross sectional configuration of a set of mounting slotsfor holding terminals;

FIG. 5 is an enlarged plan view of the. mounting section of the housingstructure illustrating the relationship of terminals positioned inmounting slots formed in the housing element;

FIG. 6 is an enlarged sectional plan view of a portion of the housingillustrating the relationship of a terminal to the slots in the mountingsections of the housing elements; and

FIG. 7 is an enlarged perspective view of a preferred embodiment of theterminals.

Referring now to the drawings in greater, a variable transformer unit orassembly 10 forming a preferred embodiment of the invention is shownexploded in FIG. 1 to illustrate the structure of the components of thetransformer unit. The variable transformer unit 10 includes a core andwinding assembly 12, a drive shaft and con tact arm assembly 14 and adial and mounting plate assembly 16. The core and winding assembly 12includes a spiral wound electrical winding 18 which is connected tometallic terminals 20. The terminals 20 are fixedly mounted on amounting area 22 of an insulative core housing 24 which is formed of aphenolic plastic and is best seen in FIG. 2 taken in conjunction withFIG. 1. The insulative housing 24 includes a pair of substantiallyidentical cup-shaped housing elements or sections 26 and 28 which encasean annular magnetic core 30. The mounting area 22 is formed by a pair ofradially outwardly projecting mounting bosses or sections 32 and 34which are integrally formed with the generally toroidal housing elements26 and 28. The housing elements 26 and 28 are normally retained by theelectrical winding 18 with open end face surfaces 38 and 40 in abuttingengagement to position the mounting sections 32 and 34, as shown in FIG.1, to form mounting area 22.

The drive shaft and contact arm assembly 14 includes a contact assembly42 which is mounted on a central axially extending drive shaft 44. Thecontact assembly 42 includes a contact arm unit 48 upon which a movableor wiper contact 50 is mounted. When the transformer unit 10 isassembled, the wiper 50 engages the electrical winding 18 and is movableto vary the output of the transformer unit 10. Insulation is ground orotherwise abraded from the electrical winding 18 to form a track whichcan be plated in a well-known manner with rhodium or other suitablemetal to improve electrical connections between the contact 50 and toimprove wear resistance of the electrical winding 18 in the area ortrack where the contact 50 engages the winding.

The dial plate mounting assembly 16 includes a dial plate 54, havingsuitable indicia thereon, which is mounted on a backing or mountingplate 56 which is in turn fixedly connected to the housing assembly 24.A knob 58 is connected to the drive shaft 44 and includes a pointersection 60 which cooperates with the indicia on the dial plate 54 toindicate the position of the movable contact 50 relative to theelectrical winding 18. The structure and functional interrelationship ofthe core and winding assembly 12, the drive shaft and contact armassembly 14 and the dial mounting plate assembly 16 are well known tothose skilled in the art. A preferred embodiment of these assemblies isset forth in application Ser. No. 456,- 978 filed on May 19, 1965 byEllin for Variable Transformer with Winding Holding Core Housing, nowissued as U.S. Patent No. 3,316,517. Those who are interested in thespecific structure of these assemblies and their interrelationship arereferred to this application.

The mounting sections 32 and 34 are substantially identical instructure. Therefore, only the structure of the mounting section 34 willbe described in detail, it being understood that the mounting section 32is substantially the same in structure as the mounting section 34. Themounting section 34 is shown in greater detail in FIGS. 3 and 4 andincludes a plurality of parallel generally T- shaped terminal mountingslots or grooves 62, 64 and 66. The T-slots 62 through 66 have generallyrectangular axially extending body sections 68, 70 and 72 which extendfrom open ends 76, 78 and 80 at the face wall 40 to transverselyextending end surfaces or walls 84, 86 and 88. The T-slots 62 through 66also include axially extending head sections 90, 92 and 94 (see FIG. 4)which are offset transversely relative to a central axis of the bodysections 68 through 72. It should be noted that the head sections 90 and94 are offset in a first direction, that is to the left, as viewed inFIG. 4, while the head section 92 is offset in a second direction, thatis to the right as viewed in FIG. 4. The head sections 90, 92, 94, arepositioned inwardly of the 'body sections 68 through 72 and areseparated from the body sections by transversely projecting shoulders96.

Referring now to FIG. taken in connection with FIG. 2, it can be seenthat the mounting area 22 is formed by positioning the housing elements26 and 28 with face surfaces 38 and 40 of the mounting sections 32 and34 in abutting engagement. The mounting sections 32 and 34 are orientedso that the T-slots which are integrally formed with the mountingsection have their open ends adjacent to each other and body sections inlongitudinal or axial alignment. However, since the housing element 26is rotated 180 relative to the position of the substantially identicalhousing element 28, the offset head sections of the T-slots are not inalignment.

This misalignment of the head sections of the T-slots is best seen inFIG. 5. The T-slots in the mounting section 32 have been designated inFIG. 5 with numerals similar to the numerals used in connection with theT- slots in the mounting section 34. However, the suflix letter a hasbeen added to the numerical designation for the T-slots in the mountingsection 32 in order to avoid confusion. The alignment of the mountingsections 32 and 34 results in the T-slot 62 in the mounting section 34being opposite to T-slot 66a in the mounting section 32 while the T-slot66 in the mounting section 34 is opposite to the T-slot 62a in themounting section 32. The center T-slots 64 and 64a are in generalalignment with each other. However, it should be noted that the headsection 911 of the T-slot 62 is offset relative to the head section 94aof the T-slot 66a. Therefore, only the body sections of the T-slots 62and 66a are aligned. From a further inspection of FIG. 5, it can be seenthat the head section 92 of 4 the T-slot 64 is offset relative to thehead section 92a of the T-slot 64a. Similarly, the head section 94 ofthe T- slot 66 is offset relative to the head section a of the T- slot62a.

This offsetting interrelationship between the head sections of theT-slots is shown in greater detail in FIG. 6. From FIG. 6 it can be seenthat a longitudinally extending transversely outer sidewall of the headsection 90 is located outwardly of a longitudinally extendingtransversely outer side wall or surface 102 of the head section 94a ofthe T-slot 66a. This offset relationship of the side walls 100 and 102provides a transversely extending positioning surface 186 which isengaged by a positioning tab or ear 108 of the terminal 20 which ismounted in the T-slot 62. The end wall 84 of the T-slot 62 is engaged byan oppositely extending positioning tab or ear 110 to fixedly locate theterminal 20 against longitudinal movement in the T-slot 62. If aterminal 20 was mounted in the T-slot 66a, the terminal would beoriented with the positioning ear or tab 110 in engagement with an endwall 88a of the T-slot 66a. The positioning ear or tab 108 would engagea positioning surface 112 formed by the offset between the head sections90 and 94a at an outward or opposite end of the T-slot 66a. It should benoted that the terminal 20 engages the face surface 38 of the housingelement 26 at the positioning surface or section 106 to fixedly retainor hold the terminal against longitudinal movement relative to theT-slot 62. Similarly, if the terminal 20 was mounted in the T-slot 66a,the terminal would engage the surface or offset shoulder 112 formed bythe surface 40 at the open end of the housing element 28.

The structure of the terminal 20 is illustrated in greater detail inFIG. 7. The terminal 20 includes a base 114 from which the positioningears or tabs 108 and 110 extend longitudinally outwardly.

When the terminals 20 are mounted in the slots in the mounting sections32 and 34, they are retained against radially outward movement relativeto the housing sections 26 and 28 by the shoulders 96 of the T-slotswhich engage the base section 114 of the terminals. A pair of connectorsections 116 and 118 extend upwardly from the base 114. The connectorsection 116 includes a hole or aperture 122 to which a wire fromapparatus associated with the variable transformer 10 can be soldered.The connector section 116 is also advantageously formed to receiveslip-on type connectors to enable the transformer 10 to be connected toassociated circuitry without the time-consuming process of soldering.The connector section 118 is soldered to leads extending from theelectrical winding 18.

Turning once again to a consideration of FIG. 5, taken in conjunctionwith FIG. 6, a plurality of grooves or slots 126 and 128 are formed inthe mounting area 22 for receiving wires or leads 130 which areconnected to the terminals 20 and the coil 18. The grooves 126 and 128are formed by recesses 132 (see FIGS. 3 and 6) which extend inwardlyfrom the face surfaces 38 and 40 of the housing elements 26 and 28. Theleads 130 extend through the grooves 126 and 128, which have a generallyU-shaped cross section, into the body sections 68 and 72 of the T- slots62 and 66. Since the leads 130 are positioned in the grooves 126 and 128beneath the surfaces of the mounting sections 32 and 34, the leads areprotected and positioned for connection to the terminals by the grooves.

In view of the foregoing remarks, it will be apparent to those skilledin the art that the housing assembly 24 is assembled by slidingterminals 20- into the slots 62 and 66 in mounting section 34 andsliding a third terminal 20 into the slot 64a of the mounting section32. The terminals will be retained or held against longitudinal movementrelative to the slots by the abutting engagement of the positioning tabs108 and 110 with the face surface of the opposite or opposing housingelement. Thus, the positioning tabs 108 of the terminals 20 mounted inthe slots 62 and 66 engage the face surface 38 of the housing element 26while the positioning tab 110 of the terminal 20 mounted in the slot 64aengages the base surface 40 of the housing element 28. This engagementbetween the terminals and the opposite housing element results from thetransverse offset of the head sections of the T-slots. The terminals 20will be retained against radially outward movement relative to theT-slots by the shoulders 96 which project over the base section 114 ofthe terminals 20. It should be noted that the mounting tabs 108 and 110are positioned within the relatively large offset portion of the headsections 90 through 94 to enable the connector sections 116 and 118 ofthe terminals to extend upwardly through the body sections 68 through 72of the T-slots. After the terminals 20 have been slid into position inthe -slots, the electrical winding 18 is Wound around the housing tofixedly interconnect the housing sections 26 and 28 as shown in FIG. 1.The leads from the electrical winding 18 are then connected to theterminals 20. It should be noted that the connector sections 118 of theterminals 20 are maintained in a spaced apart relationship relative toeach other by the positioning tabs 108 and 110 to facilitate connectingof the electrical winding to the terminals 20.

While particular embodiments of the invention have been shown, it shouldbe understood, of course, that the invention is not limited theretosince many modifications may be made; and it is, therefore, contemplatedto cover by the appended claims any such modifications as fall withinthe true spirit and scope of the invention.

What is claimed is:

1. A variable transformer comprising: an annular magnetic core; anelectrical winding on said core; an electrically insulative housingbetween said core and said winding, said housing including first andsecond rigid housing elements, said housing also including a mountingsection in which a plurality of slots is formed; and a plurality ofterminal members slidably mounted in the slots, said terminal membersbeing in abutting engagement With first surfaces of said first housingelement and with second surfaces of said second housing element tofixedly position said terminal members in the slots, wherein the slotsin said housing have a relatively narrow body section and a relativelywide head section located inwardly of the body section and wherein saidterminal members include a relatively wide base section which isslidably received in the head section of the slot to retain the terminalmembers against outward movement relative to said housing.

2. A variable transformer as set forth in claim 1 wherein said slots aregenerally T-shaped in cross section.

3. A variable transformer as set forth in claim 1 and further including:a groove formed in said housing and extending transversely to andintersecting one of the slots in said housing; and a wire connected at afirst end to said electrical winding and connected at a second end to aterminal member in the slot intersected by the groove, said wire beingpositioned in the groove beneath a plane of an outer surface of themounting section.

4. A variable transformer comprising: an annular magnetic core; anelectrical winding on said core; an electrically insulative housingbetween said core and said Winding, said housing including first andsecond rigid housing elements aligned with open end faces in abuttingengagement to form an enclosure for said core; a first mounting sectionconnected to said first housing element and at least partially defininga first longitudinally extending slot which includes a relatively narrowlongitudinally extending body section intersecting the face surface ofsaid first housing element and a relatively Wide longitudinallyevtending head section which also intersects the face surface of saidfirst housing element; a second mounting section connected to saidsecond housing element and at least partially defining a secondlongitudinally extending slot which includes a relatively narrowlongitudinally extending body Section which intersects the face surfaceof said second housing element and a relatively wide longitudinallyextending head section which also intersects the face surface of saidsecond housing element; first terminal means mounted in said first slotfor connecting electrical circuitry to the variable transformer; saidfirst terminal means engaging the face surface of said second housingelement and a transversely extending end surface of said first slot toretain said first terminal means against longitudinal movement relativeto said first mounting section, said first terminal means including abase section positioned in engagement with the head section of saidfirst slot to retain said first terminal means against outward movementrelative to said first mounting section; and second terminal meansslidably mounted in said second slot for connecting electrical circuitryto the variable transformer, said second terminal means engaging theface surface of said first housing element and a transversely extendingend surface of said second slot to retain said second terminal meansagainst longitudinal movement relative to said second mounting section,said second terminal means including a base section positioned inengagement with head section of said second slot to retain said secondterminal means against outward movement relative to said second mountingsection.

5. A variable transformer assembly as set forth in claim 4 wherein: saidfirst terminal means includes an upstanding connector section and alongitudinally extending positioning tab, said positioning tab of saidfirst terminal means engaging the face surface of said housing elementto space the upstanding connector section of said first terminal meansapart from the face surface of said second housing element; and saidsecond terminal means includes an upstanding connector section and alongitudinally extending positioning tab, said positioning tab of saidsecond terminal means engaging the face surface of said first housingelement to space the upstanding connector setcion of said secondterminal means apart from the face surface of said first housingelement.

6. A variable transformer comprising: an annular magnetic core; anelectrically insulative housing between said core and said winding, saidhousing including first and second rigid housing elements aligned withopen end face surfaces in abutting engagement to form an enclosure forsaid core; a first mounting section integrally formed with said firsthousing element and at least partially defining a first set oflongitudinally extending slots, each slot of said first set oflongitudinally extending slots including a relatively narrowlongitudinally extending body section which intersects the face surfaceof said first housing element at an open end of the body section and arelatively wide longitudinally extending head section which intersectsthe face surface of said first housing element at an open end of thehead section, the head section being located radially inwardly of saidbody section and offset transversely relative to said body section; asecond mounting section integrally formed with said second housingelement and at least partially defining a second set of longitudinallyextending slots, each slot of said second set of longitudinallyextending slots including a relatively narrow longitudinally extendingbody section which intersects the face surface of said second housingelement at an open end of the body section and a relatively widelongitudinally extending head section which intersects the face surfaceof said second housing element at an open end of the head section, theopen end of the body section of each slot of said second set of slotsbeing positioned in alignment with the open end of the body section ofsaid first set of slots, the head section of said first set of slotsbeing located radially inwardly of and offset relative to the bodysection of said first set of slots, and the head section of said secondset of slots being located radially inwardly of the body section of saidsecond set of slots and offset relative to both the body sections ofsaid second set of slots and the head section of said first set ofslots; first terminal means mounted in a slot of said first set of slotsfor connecting electrical circuitry to the variable transformer, saidfirst terminal means extending through the open end of the head sectionof a slot of said first set of slots to engage the face surface of saidsecond housing element and hold said first terminal means againstmovement relative to said first housing element; and second terminalmeans mounted in a slot of said second set of slots for connectingelectrical circuitry to the variable transformer, said second terminalmeans extending through the open end of the head section of a slot ofsaid second set of slots to engage the face surface of said firsthousing element and hold said second terminal means UNITED STATESPATENTS 5/1965 Helberg 336-192 4/1967 Ellin 336149 LEWIS H. MYERS,Primary Examiner.

l0 THOMAS J. KOZMA, Assistant Examiner.

US. Cl. X.R. 336--l98, 149

